Ice removal systems are known in the art. For example, see U.S. Pat. No. 6,027,075, the disclosure of which is hereby incorporated herein by reference. See also published U.S. patent application Ser. Nos. 2002/0017466 (published Feb. 14, 2002) and 2001/0052731 (published Dec. 20, 2001), both of which are hereby incorporated herein by reference. Ice removal structures/systems of these patents/applications act so as to modify (e.g., weaken) ice adhesion strength between ice and selected materials in order to facility ice removal. Actions such as scraping ice off of vehicle windshields is made less difficult when the ice adhesion strength is weakened (i.e,. the ice is more easily removed once the adhesion strength has been weakened).
FIGS. 1-2 illustrate a conventional ice removal system as described in the aforesaid '075 Patent. FIG. 1 is a top plan view, while FIG. 2 is a cross sectional view taken along section line A—A. The ice removal system of FIGS. 1-2 acts to reduce the adhesion strength of ice 102 formed on surface 104a of material 104 (e.g. glass). The ice removal system includes a conductive grid 106 formed on the substrate 104, with an insulator 108 therebetween. Power supply (e.g., battery) 109 and voltage regulator subsystem 112 are in electrical communication with conductive grid 106. The ice removal system/structure of FIGS. 1-2 forms a circuit that includes substrate 104 (e.g., glass doped so as to be conductive, or other conductive material), conductive grid 106, and power supply 109. Insulating material 108 causes grid 106 to be electrically insulated from substrate 104.
Still referring to FIGS. 1-2, when no ice is present on the substrate 104, little or no electric current flows between conductive grid 106 and substrate 104. However, when ice 102 forms on surface 104a of substrate 104, the ice is at least partially conductive so as to complete an electrical circuit between conductive grid 106 and substrate 104. In other words, the ice completes an electrical circuit that includes power supply 109, conductive grid 106, ice 102, and substrate 104. In essence, the ice shorts at least one section of the grid to complete this circuit. The resulting current flowing through the aforesaid circuit, upon application of voltage, weakens the ice adhesion strength as explained in U.S. Pat. No. 6,207,075, making it easier for the ice to be removed from the substrate 104 and grid 106 by scraping, wind, melting, and/or the like.
Unfortunately, if used in the context of vehicle windshields, the structure of FIGS. 1-2 (and the '075 Patent) would be undesirable in that it would be very susceptible to damage caused by normal vehicle operation in typical environmental conditions. The ice removal structure of FIGS. 1-2 is rather fragile, and prone to damage such as scratching, peeling off, fracturing, and/or the like.
Accordingly, it will be appreciated by those skilled in the art that there exists a need in the art for a more durable ice removal structure/system for use in applications such as vehicle windows (e.g., windshields and/or backlites), or other exterior windows.